Method for preparing high-purity quartz by fractional preferential flotation and high-purity quartz

Abstract

This invention provides a method for preparing high-purity quartz using graded preferential flotation, and the high-purity quartz itself. The method includes crushing the quartz ore to obtain crushed products with a particle size of less than 50 mm, mechanically scrubbing and desliming to obtain first quartz particles; grinding and screening the first quartz particles to obtain particles of +70 mesh to -20 mesh, followed by mechanical scrubbing and desliming to obtain second quartz particles; grinding the second quartz particles with a screening sieve to obtain particles of 70 to 150 mesh, followed by magnetic separation to obtain third quartz particles; subjecting the third quartz particles to multiple graded preferential flotation stages to obtain fourth quartz particles; and acid washing the fourth quartz particles, followed by filtration, washing, and drying to obtain high-purity quartz. This invention reduces the amount of gangue minerals such as clay and mica entering subsequent beneficiation stages; it enables graded collection and separation of different gangue minerals in a weakly alkaline environment, reducing the use of strong acids or HF acids, making it more environmentally friendly; and it allows for the separate collection and utilization of gangue minerals.

Description

Technical Field

[0001] This invention belongs to the field of high-purity mineral materials technology, specifically, it relates to a method for preparing high-purity quartz by graded preferential flotation and the high-purity quartz. Background Technology

[0002] High-purity quartz refers to quartz sand with extremely high purity (SiO2 content of over 99.9%) that retains its crystalline state. High-purity quartz is a mineral product obtained by refining ores such as crystal, vein quartz, and granite pegmatite. It is the material basis for high-end products in the silicon industry and is widely used in strategic emerging industries. With the rapid development of new technologies and materials industries globally, the demand for high-purity quartz continues to grow, especially in the semiconductor, optical communication, and photovoltaic fields. Based on its SiO2 content, high-purity quartz can be classified into different grades.

[0003] Currently, the domestic production of high-purity quartz mainly relies on natural crystal or high-quality vein quartz ore. The process for producing high-purity quartz from natural crystal and high-quality vein quartz involves purifying and removing impurities through processes such as calcination, water quenching, crushing and grinding, magnetic separation, flotation, and acid washing. However, directly using whole quartz raw materials can easily result in processing areas of different qualities, or even those containing significant impurities, together. This leads to a lower-than-expected average purity in the final product, making it impossible to produce high-purity quartz. Furthermore, it is difficult to remove lattice impurities from the quartz.

[0004] Therefore, it is of great significance to study a method for preparing high-purity quartz that directly uses raw quartz ore, involves zone screening, achieves the required purity, and is environmentally friendly. Summary of the Invention

[0005] The purpose of this invention is to address at least one of the aforementioned deficiencies in the prior art. For example, one objective of this invention is to provide a high-purity quartz preparation process that reduces the amount of gangue minerals such as clay and mica entering subsequent beneficiation stages; a second objective of this invention is to provide a green and environmentally friendly method for preparing high-purity quartz; a third objective of this invention is to provide a method that enables the separate collection and utilization of gangue minerals; and a fourth objective of this invention is to provide a high-purity quartz.

[0006] To achieve the above objectives, the present invention provides a method for preparing high-purity quartz by graded preferential flotation, the method comprising the following steps:

[0007] The raw quartz ore is crushed to obtain crushed products with a particle size of less than 50 mm. The products are then mechanically scrubbed and deslimed to obtain the first quartz particles.

[0008] The first quartz particles were ground and screened, and the particles screened from +70 mesh to -20 mesh were mechanically scrubbed and deslimed to obtain the second quartz particles.

[0009] The second quartz particles are ground with a screening sieve, and the 70-150 mesh particles are then magnetically separated to obtain the third quartz particles.

[0010] The third quartz particles were subjected to multiple fractional preferential flotation to obtain the fourth quartz particles.

[0011] The fourth quartz particles were acid-washed, filtered, washed and dried to obtain high-purity quartz.

[0012] Optionally, the quartz ore includes vein quartz, quartzite, quartz sandstone, granite pegmatite, or natural sand, and the crushing is performed using one or more of a jaw crusher, gyratory crusher, and cone crusher, with the crushed product having a particle size distribution of less than 50 mm.

[0013] Alternatively, the mechanical scrubbing and desliming can be performed using one or more of a hydrocyclone, a spiral classifier, and a sand washing machine.

[0014] Alternatively, the crushed product is subjected to mechanical scrubbing and desliming, with the desliming endpoint being a suspension solids content in the scrubbing liquid of less than 1 g / L.

[0015] Alternatively, the grinding process may employ one or more of the following: ball mill, rod mill, autogenous mill, and semi-autogenous mill.

[0016] The screening process uses multi-layer or single-layer vibrating screens or spoke screens. The material above the 20-mesh screen is returned for re-grinding, and the material below the 70-mesh screen is discarded.

[0017] Alternatively, the inspection screening involves setting a 70-mesh multi-layer or single-layer vibrating screen, grid screen, or spoke screen at the discharge port of the grinding mill, and simultaneously setting a screen behind it to discard mineral powder with a mesh size lower than 150.

[0018] Alternatively, the mechanical scrubbing and desliming of the first-stage grinding product may employ one or more of the following: hydrocyclone, spiral classifier, and sand washing machine.

[0019] Alternatively, the mechanical scrubbing and desliming of the first-stage grinding product is terminated when the suspended solids content in the scrubbing liquid is less than 1 g / L.

[0020] Alternatively, the magnetic separation may employ a high-intensity magnetic separator with a maximum magnetic field strength of 10,000 Gs or higher.

[0021] Alternatively, the multiple-stage preferential flotation is prepared by using glacial acetic acid or hydrochloric acid to prepare an acidic flotation reagent solution of dodecylamine and sodium oleate, and then mixing it with an alkaline slurry to obtain a uniformly stirred preferential flotation slurry.

[0022] Optionally, the mass fraction of glacial acetic acid or hydrochloric acid in the acidic flotation reagent solution should be 1%–10%, while ensuring that the concentration of dodecylamine in the well-mixed slurry is 1.2–3.0 × 10⁻⁶. -4 The concentration of sodium oleate is 0.6–1.5 × 10 mol / L. -4 mol / L, with a pulp mass concentration of 20–30%.

[0023] Alternatively, the graded preferential flotation pulp may include the following stages:

[0024] The first stage of preferential flotation requires the use of NaOH, KOH or NH3 and acidic flotation reagents to prepare a pulp with pH = 12 ± 0.5 to preferentially float tourmaline. If the original ore has a high tourmaline content, the first stage of preferential flotation can be repeated.

[0025] The secondary-stage preferential flotation pulp needs to be prepared with added water and acidic flotation reagents to a pH of 11 ± 0.5 to preferentially float out mica. If the raw ore has a high mica content, the secondary-stage flotation can be repeated.

[0026] The three-stage preferential flotation pulp needs to be prepared with added water and acidic flotation reagents to a pH of 10 ± 0.5 to float feldspar. If the original ore has a high feldspar content, the three-stage flotation can be repeated.

[0027] Alternatively, the pickling acid solution may be one or more of phosphoric acid, hydrofluoric acid, hydrochloric acid, and nitric acid, wherein the concentration range of phosphoric acid is 0–4 mol / L, the concentration range of hydrofluoric acid is 0–2 mol / L, the concentration range of hydrochloric acid is 0.5–2 mol / L, and the concentration range of nitric acid is 0–2 mol / L.

[0028] Optionally, the solid-liquid mass ratio of pickling is 1:2 to 10, and the pickling environment can be atmospheric pickling at 40 to 99°C or hot-press pickling at 100 to 200°C.

[0029] Alternatively, the filtration may employ one or more of a thickener, a vacuum filter press, and a plate and frame filter press.

[0030] Alternatively, the washing process involves repeatedly rinsing the acid-washed quartz with deionized water until the pH of the filtrate is greater than 6.5.

[0031] Alternatively, the drying process may employ one or more of freeze drying, vacuum drying, and electrothermal drying.

[0032] In another aspect, the present invention provides a high-purity quartz, which is prepared by the above-described method, wherein the high-purity quartz has a SiO2 mass fraction greater than 99.9% and has an α-quartz crystal phase.

[0033] In another aspect, the present invention provides an application of high-purity quartz, wherein the high-purity quartz with a SiO2 mass fraction of less than or equal to 99.995% is used for deep purification of ultra-white quartz glass raw materials, high-purity quartz glass instruments and ultra-high-purity quartz raw materials to obtain ultra-high-purity quartz with higher purity.

[0034] High-purity quartz with a SiO2 mass fraction greater than 99.995% is used as a raw material for quartz glass in precision optics or for high-purity quartz crucibles used in Czochralski single-crystal silicon pulling.

[0035] Compared with the prior art, the beneficial effects of the present invention may include at least one of the following:

[0036] 1) This invention reduces the amount of gangue minerals such as clay and mica entering the subsequent beneficiation stage.

[0037] 2) This invention enables the graded collection of different gangue minerals in a weakly alkaline environment, reducing the use of strong acids or HF acids and making it more environmentally friendly.

[0038] 3) This invention enables the separate collection and utilization of gangue minerals through graded flotation. Detailed Implementation

[0039] In the following, the method for preparing high-purity quartz by graded preferential flotation according to the present invention and the high-purity quartz will be described in detail with reference to exemplary embodiments.

[0040] Exemplary Example 1

[0041] This exemplary embodiment provides a method for preparing high-purity quartz by graded preferential flotation, the method comprising the following steps:

[0042] S01: The raw quartz ore is crushed to obtain crushed products with a particle size of less than 50mm. The products are then mechanically scrubbed and deslimed to obtain the first quartz particles.

[0043] In this embodiment, the raw quartz ore can be quartzite, vein quartz, or granite pegmatite. Crushing can be performed using one or more of the following: a zirconia-lined or pure iron-lined jaw crusher, a gyratory crusher, or a cone crusher. The crushed quartz ore can produce a particle size of less than 50mm to initially crush the quartz, exposing some intercrystalline impurities, which facilitates better subsequent scrubbing and desliming. Mechanical scrubbing and desliming of the crushed product is performed using one or more of the following: a hydrocyclone, a spiral classifier, or a sand washer. The desliming endpoint is when the suspended solids content in the scrubbing liquid is less than 1g / L. If the scrubbing liquid exceeds this value, it cannot completely carry away the solid particles in the suspension, causing them to settle again on the quartz particle surface, affecting subsequent purification processes. Reaching this value ensures that fine clay or mica impurities on the quartz particle surface flow out with the scrubbing liquid, preventing them from being carried into later beneficiation processes and affecting the beneficiation of high-purity quartz. The purpose of scrubbing and desliming is to remove the attached clay and excessively fine ore particles from the surface of the quartz, so as to avoid affecting the subsequent beneficiation stage.

[0044] S02: Grind and screen the first quartz particles, and mechanically wash and deslim the +70 mesh to -20 mesh particles to obtain the second quartz particles.

[0045] In this embodiment, the first quartz particles are ground and screened. Grinding can be performed using one or more of a ball mill, rod mill, autogenous mill, and semi-autogenous mill. The lining material can be one of zirconium oxide, alumina, tungsten carbide, and pure iron. Screening can be performed using multi-layer, single-layer vibrating screens, or spoked screens. Materials passing through a 20-mesh screen are returned for re-grinding, while materials passing through a 70-mesh screen are discarded. The purpose of selecting zirconium oxide, alumina, tungsten carbide, or pure iron for the mill lining is to avoid contamination of the quartz by the lining due to its lower hardness compared to quartz, or to ensure that the contaminant source remains pure iron for better removal. Selecting a grinding and screening product particle size between +70 mesh and -20 mesh further liberates the product, exposing embedded amorphous impurities and clay, facilitating subsequent impurity removal.

[0046] Mechanical scrubbing of the selected +70 mesh to -20 mesh particles can be performed using one or more of a hydrocyclone, spiral classifier, and sand washer. The purpose of further scrubbing and desliming after grinding the quartz to a finer particle size is to expose the finely embedded gangue minerals and separate and remove them through mechanical scrubbing. The key to scrubbing is ensuring the solid content of the suspension is below 1 g / L. If the scrubbing liquid exceeds this value, it cannot completely carry away the solid particles from the suspension as it flows out, causing the solid particles to settle again on the surface of the quartz particles, affecting subsequent purification processes. Reaching this value ensures that fine clay or mica impurities on the surface of the quartz particles flow out with the scrubbing liquid, preventing them from being carried into later separation processes and affecting the separation of high-purity quartz.

[0047] S03: Grind the second quartz particles with a screening screen, screen the particles to -70 to +150 mesh and then perform magnetic separation to obtain the third quartz particles.

[0048] In this embodiment, the grinding of the second quartz particles with inspection sieving can be performed using one or more of ball mills, rod mills, autogenous mills, and semi-autogenous mills. The inspection sieving involves setting a 70-mesh multi-layer or single-layer vibrating screen, grid screen, or spoke screen at the mill discharge port, with a subsequent screen to discard ore powder smaller than 150 mesh. The selection of a -70 to +150 mesh size aims to maximize the separation of individual particles while meeting the particle size requirements for high-quality, high-purity quartz sand, thereby better removing gangue minerals and other impurities.

[0049] Magnetic separation is performed on the screened 70-150 mesh particles. Magnetic separators with a maximum magnetic field strength of 10,000 Gs or higher, such as 10,000 Gs, 16,000 Gs, 35,000 Gs, etc., can be used. The magnetic separators may include permanent magnet roller type high-intensity magnetic separators, high-gradient superconducting magnetic separators, double-roll wet high-intensity magnetic separators, or vertical ring high-gradient magnetic separators, etc., to separate and remove strongly magnetic and weakly magnetic gangue minerals from quartz ore.

[0050] S04: The third quartz particles are subjected to multiple classification and preferential flotation to obtain the fourth quartz particles.

[0051] In this embodiment, the third quartz particle undergoes a three-stage preferential flotation process. A dodecylamine and sodium oleate are prepared into an acidic flotation reagent solution using glacial acetic acid or hydrochloric acid, and then stirred and mixed with an alkaline slurry. The mass fraction of glacial acetic acid or hydrochloric acid in the acidic flotation reagent solution can be 1%–10%, for example, 2%, 6%, or 9%. Simultaneously, it is necessary to ensure that the concentration of dodecylamine in the mixed slurry is 1.2–3.0 × 10⁻⁶. -4 mol / L, for example 1.3 × 10⁻⁶ -4 mol / L, 2.3×10 -4 mol / L or 2.6×10 -4 mol / L, etc.; the concentration of sodium oleate is 0.6~1.5×10 -4 mol / L, for example 0.7 × 10⁻⁶ -4 mol / L, 1.2×10 - 4 mol / L or 1.4×10 -4 The concentration of the pulp is 20-30%, such as 21%, 25%, or 29%. The purpose of selecting this concentration range is to control the concentration to be too high while meeting the minimum concentration required for flotation, so as to avoid waste of reagents and increase economic costs.

[0052] In this embodiment, the number of stages of priority flotation can be less than or more than three times. The specific number of flotations depends on the content and separation of gangue minerals corresponding to each stage of flotation. For example, if the first stage of flotation is mainly for tourmaline, and the tourmaline content is high, the first stage of flotation needs to be repeated multiple times. If the raw ore contains more tourmaline and a small amount of mica and feldspar, two stages of first stage flotation and one stage of second and third stage flotation can be performed, for a total of four flotations. If the raw ore contains more mica and feldspar and a small amount of tourmaline, one stage of first stage flotation and two stages of second and third stage flotation can be performed, for a total of five flotations. If the raw ore contains a small amount of mica and feldspar but no tourmaline, one stage of second and third stage flotation can be performed, for a total of two flotations.

[0053] The first stage of flotation requires a pulp prepared with NaOH, KOH, or NH3 and acidic flotation reagents to a pH of 12 ± 0.5, which preferentially floats tourmaline. If the original ore has a high tourmaline content, the first stage of flotation can be repeated. At this pH, tourmaline and other minerals have good floatability in this reagent system, which can achieve preferential flotation of tourmaline. At the same time, the first addition of acidic collector solution to the alkaline pulp can also ensure that the pH of the three flotations decreases gradually from high to low.

[0054] The graded flotation pulp for the two-stage flotation needs to be prepared with added water and acidic flotation reagents to a pH of 11 ± 0.5 to preferentially float mica. If the raw ore has a high mica content, the two-stage graded flotation can be repeated. At this pH, mica and other minerals have good floatability in this reagent system, which can achieve preferential flotation of tourmaline. At the same time, the second addition of acidic collector solution to the alkaline pulp can also ensure that the pH of the three flotations decreases from high to low.

[0055] The three-stage flotation pulp needs to be prepared with added water and acidic flotation reagents to a pH of 10 ± 0.5 to float feldspar. If the original ore has a high feldspar content, the three-stage flotation can be repeated. At this pH, feldspar and other minerals have good floatability in this reagent system, which can achieve the flotation of feldspar. At the same time, the addition of acidic collector solution to the alkaline pulp for the third time can also ensure that the pH of the three flotations decreases from high to low.

[0056] S05: The fourth quartz particles are acid-washed, filtered, washed and dried to obtain high-purity quartz.

[0057] In this embodiment, the acid washing of the fourth quartz particles can be performed using one or more of phosphoric acid, hydrofluoric acid, hydrochloric acid, and nitric acid. The concentration range of phosphoric acid can be 0–4 mol / L, for example, 1 mol / L, 2 mol / L, or 3 mol / L; the concentration range of hydrofluoric acid can be 0–2 mol / L, for example, 1 mol / L or 2 mol / L; the concentration range of hydrochloric acid can be 0.5–2 mol / L, for example, 0.6 mol / L, 1 mol / L, or 1.9 mol / L; and the concentration range of nitric acid can be 0–2 mol / L, for example, 1 mol / L or 1.9 mol / L. The purpose of using acids within this concentration range is to leach the metal oxides in the flotation concentrate quartz while avoiding passivation or a significant increase in economic and environmental costs due to excessively high concentrations.

[0058] The solid-liquid mass ratio for pickling can be 1:2 to 10, such as 1:3, 1:5, 1:7, or 1:9. The pickling environment can be atmospheric pickling at 40 to 99°C or hot-press pickling at 100 to 200°C. Filtration can be carried out using one or more of a thickener, vacuum filter press, and plate and frame filter press. Washing can be done by repeatedly rinsing the pickled quartz with deionized water until the pH of the filtrate is greater than 6.5. Drying can be carried out using one or more of freeze drying, vacuum drying, and electrothermal drying.

[0059] The purpose of selecting a solid-liquid ratio of 1:2 to 10 for pickling is to ensure that the acid completely submerges the quartz particles, while preventing insufficient acid from leaving impurities on the quartz particle surface undissolved. The purpose of selecting a pickling temperature of 40–99℃ for atmospheric pressure pickling or 100–200℃ for hot-press pickling is to improve pickling efficiency through heating and pressurization, avoiding excessively slow reaction rates that lead to prolonged process times and reduced production efficiency. Temperatures below 200℃ are chosen because reaction conditions higher than this are difficult to achieve on conventional industrial equipment, and excessively high temperatures can easily cause a surge in tank pressure, leading to leaks and other safety accidents. Cleaning the quartz until the filtrate pH is greater than 6.5 is to prevent acid residue from adhering to the quartz particle surface, which could harm equipment and operators during drying or later use. It also ensures that the solution on the quartz surface is thoroughly rinsed away, preventing contamination.

[0060] Exemplary Example 2

[0061] This exemplary embodiment provides a high-purity quartz prepared by the method described in Exemplary Embodiment 1. The high-purity quartz has a SiO2 mass fraction greater than 99.9% and possesses an α-quartz crystal phase.

[0062] Exemplary Example 3

[0063] This exemplary embodiment provides an application of high-purity quartz, which is the high-purity quartz described in Exemplary Embodiment 2. High-purity quartz with an SiO2 mass fraction of 99.995% or less can be used as a raw material for ultra-white quartz glass and high-purity quartz glass instruments (e.g., quartz tubes, quartz ingots, or optical quartz glass devices). High-purity quartz with an SiO2 mass fraction of 99.9% to 99.995% can also be used as a raw material for ultra-high-purity quartz for deep purification to obtain ultra-high-purity quartz with even higher purity. High-purity quartz with an SiO2 mass fraction greater than 99.995% can be used as a raw material for precision optical quartz glass or for high-purity quartz crucibles used in pulling single-crystal silicon.

[0064] To better understand the exemplary embodiments of the present invention described above, further explanation is provided below with reference to specific examples.

[0065] Example 1

[0066] Sample JX03-1 is a quartz-bearing weathered gravel produced after weathering granite pegmatite. It is yellow with interspersed white and gray parts, and has an uneven grain size distribution, with the largest grain reaching 70 mm. Its chemical composition is shown in Table 1.

[0067] Table 1. Chemical composition analysis (%) of sample JX03-1

[0068]

[0069] The preparation method of this example of high-purity quartz includes the following steps:

[0070] The raw quartz ore is crushed using a zirconia-lined jaw crusher to obtain particles with a diameter of less than 50 mm; mechanical scrubbing and desliming are then performed using a sand washing machine to obtain the first quartz particles.

[0071] The first quartz particles were ground and screened using a ball mill lined with zirconium oxide and zircon balls as the grinding media. A single-layer vibrating screen was used for screening to obtain particles of +70 mesh to -20 mesh. The particles were then mechanically scrubbed and deslimed using a sand washing machine to obtain the second quartz particles.

[0072] The second quartz particles were ground with a screening sieve. The mill was a ball mill with a zirconium oxide lining and zircon balls as the grinding media. The resulting quartz particles of 70-150 mesh were then subjected to magnetic separation. A high-gradient vertical ring high-intensity magnetic separator was used for magnetic separation with a magnetic field strength of 15000 Gs to obtain the third quartz particles.

[0073] The third quartz particle was subjected to three-stage preferential flotation. The acidic flotation reagent solution contained 5% glacial acetic acid and 1.2 × 10⁻⁶ dodecylamine. -3 The concentration of sodium oleate is 0.6 × 10 mol / L.-3 In the first stage of flotation, sodium hydroxide and flotation reagents were stirred and mixed together to achieve a pulp pH of 12.1 and a dodecylamine concentration of 1.2 × 10⁻⁶ mol / L. -4 The concentration of sodium oleate is 0.6 × 10 mol / L. -4 mol / L, pulp mass concentration is 25%;

[0074] In the second stage of flotation, acidic flotation reagents are added to adjust the pulp pH to 11.2 and the pulp concentration to 22.5%.

[0075] In the three-stage flotation process, acidic flotation reagents are added to adjust the pulp pH to 10.4 and the pulp concentration to 20%, resulting in the fourth stage of quartz particles.

[0076] The fourth type of quartz particles were acid-washed, filtered, washed, and dried. The acid washing solution consisted of 0.4 mol / L phosphoric acid, 0 mol / L hydrofluoric acid, 0.5 mol / L hydrochloric acid, and 1 mol / L nitric acid. The solid-liquid mass ratio was 1:10, and the acid washing environment was 60℃ at normal pressure. The filtration was performed using a plate and frame filter press. The washing involved repeatedly rinsing the acid-washed quartz with deionized water until the pH of the filtrate was greater than 6.5. The drying was performed using electrothermal drying to obtain 3N grade high-purity quartz. The chemical composition of the obtained high-purity quartz was analyzed, and the results are shown in Table 2.

[0077] Table 2. Chemical composition analysis (ppm) of purified product from sample JX03-1

[0078]

[0079] As can be seen from Table 2, the total amount of the 17 impurity elements in the JX03-1 purified sample is less than 1000 ppm, which meets the chemical composition requirements of 3N grade high-purity quartz.

[0080] Example 2

[0081] Sample JX03-2 is vein quartz from the core of a granite pegmatite, with uneven grain size distribution, the largest grain size reaching 100 mm. Its chemical composition is shown in Table 3.

[0082] Table 3 Chemical composition analysis (%) of sample JX03-2

[0083]

[0084] The preparation method of this example of high-purity quartz includes the following steps:

[0085] The raw quartz ore is crushed using a zirconia-lined jaw crusher to obtain particles with a diameter of less than 50 mm. Mechanical scrubbing and desliming are then performed using a hydrocyclone to obtain the first quartz particles.

[0086] The first quartz particles were ground and screened using a semi-autogenous mill lined with zirconium oxide and zircon balls as the grinding media. A multi-layer vibrating screen was used to screen the particles, which were then sieved to obtain particles of +70 mesh to -20 mesh. The particles were then mechanically scrubbed and deslimed using a hydrocyclone to obtain the second quartz particles.

[0087] The second quartz particles were ground with a screening sieve. The mill was a semi-autogenous mill with a zirconium oxide lining and zircon balls as the grinding media. The resulting 70-150 mesh particles were then subjected to magnetic separation using a superconducting high-intensity magnetic separator with a magnetic field strength of 35000 Gs to obtain the third quartz particles.

[0088] The third quartz particle was subjected to three-stage preferential flotation. The acidic flotation reagent solution contained 1% hydrochloric acid and 3.0 × 10⁻⁶ dodecylamine. -3 The concentration of sodium oleate is 1.5 × 10 mol / L. -3 In the first stage of flotation, sodium hydroxide and flotation reagents were stirred and mixed together to achieve a pulp pH of 11.9 and a dodecylamine concentration of 3.0 × 10⁻⁶ mol / L. -4 The concentration of sodium oleate is 1.5 × 10 mol / L. -4 mol / L, pulp mass concentration is 30%;

[0089] In the second stage of flotation, acidic flotation reagents are added to adjust the pulp pH to 11.0 and the pulp concentration to 27%.

[0090] In the three-stage flotation process, acidic flotation reagents are added to adjust the pulp pH to 9.8 and the pulp concentration to 24%, resulting in the fourth stage of quartz particles.

[0091] The fourth type of quartz particles were acid-washed, filtered, washed, and dried. The acid washing solution consisted of 0 mol / L phosphoric acid, 0.5 mol / L hydrofluoric acid, 1.2 mol / L hydrochloric acid, and 1.4 mol / L nitric acid. The solid-liquid mass ratio was 1:5, and the acid washing environment was hydrothermal at 200℃. The filtration was performed using a vacuum filter. The washing involved repeatedly rinsing the acid-washed quartz with deionized water until the pH of the filtrate was greater than 6.5. The drying was performed using electrothermal drying to obtain 4N grade high-purity quartz. The chemical composition of the obtained high-purity quartz was analyzed, and the results are shown in Table 4.

[0092] Table 4. Chemical composition analysis (ppm) of purified products from sample JX03-2.

[0093]

[0094] As can be seen from Table 4, the total amount of the 17 impurity elements in the JX03-2 purified sample is less than 100 ppm, which meets the chemical composition requirements of 4N grade high-purity quartz.

[0095] Although the present invention has been described above in conjunction with exemplary embodiments, it should be clear to those skilled in the art that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A method for preparing high-purity quartz by graded preferential flotation, characterized in that, The method includes the following steps: S01: The raw quartz ore is crushed to obtain crushed products with a particle size of less than 50mm. The products are then mechanically scrubbed and deslimed to obtain the first quartz particles. S02: Grind and screen the first quartz particles, and mechanically wash and deslim the +70 mesh to -20 mesh particles to obtain the second quartz particles; S03: Grind the second quartz particles with inspection sieve, screen the particles to -70~+150 mesh and then perform magnetic separation to obtain the third quartz particles; S04: The third quartz particles are subjected to multiple classification and preferential flotation to obtain the fourth quartz particles; The aforementioned multiple-stage preferential flotation involves preparing an acidic flotation reagent solution using glacial acetic acid or hydrochloric acid to mix dodecylamine and sodium oleate, and then stirring and mixing this solution with an alkaline ore pulp to obtain a uniformly stirred preferential flotation ore pulp. The mass fraction of glacial acetic acid or hydrochloric acid in the acidic flotation reagent solution is 1%~10%, while ensuring that the concentration of dodecylamine in the stirred and mixed ore pulp is 1.2~3.0×10⁻⁶. -4 The concentration of sodium oleate is 0.6~1.5×10 mol / L. -4 mol / L, pulp mass concentration of 20-30%; The graded preferential flotation pulp includes the following stages: the first stage preferential flotation pulp is prepared with NaOH, KOH or NH3 and acidic flotation reagents to a pH of 12±0.5, preferentially flotating tourmaline; the second stage preferential flotation pulp is prepared with makeup water and acidic flotation reagents to a pH of 11±0.5, preferentially flotating mica; the third stage preferential flotation pulp is prepared with makeup water and acidic flotation reagents to a pH of 10±0.5, flotating feldspar. S05: The fourth quartz particles are acid-washed, filtered, washed and dried to obtain high-purity quartz.

2. The method according to claim 1, characterized in that, In step S01, the quartz ore includes vein quartz, quartzite, quartz sandstone, granite pegmatite, or natural sand. The crushing is performed using one or more of a jaw crusher, gyratory crusher, and cone crusher, and the particle size of the crushed product is below 50 mm.

3. The method according to claim 1, characterized in that, In step S01, the mechanical scrubbing and desliming process employs one or more of the following: hydrocyclone, spiral classifier, and sand washing machine. The mechanical scrubbing and desliming of the crushed products is completed when the suspended solids content in the scrubbing liquid is less than 1 g / L.

4. The method according to claim 1, characterized in that, In step S02, the grinding process employs one or more of the following: ball mill, rod mill, autogenous mill, and semi-autogenous mill. In step S02, the screening is carried out using multi-layer, single-layer vibrating screens or spoke screens, with the material above the 20-mesh screen being returned for re-grinding and the material below the 70-mesh screen being discarded.

5. The method according to claim 1, characterized in that, In step S02, the mechanical scrubbing and desliming uses one or more of a hydrocyclone, a spiral classifier, and a sand washing machine. The desliming endpoint is when the suspended solids content in the scrubbing liquid is less than 1 g / L. In step S03, the inspection and screening involves setting a 70-mesh multi-layer or single-layer vibrating screen, grid screen or spoke screen at the discharge port of the grinding mill, and setting a screen behind it to discard the -150-mesh mineral powder. In step S03, the magnetic separation uses a high-intensity magnetic separator with a maximum magnetic field strength of 10,000 Gs or more.

6. The method according to claim 1, characterized in that, In step S05, the acid solution used for pickling is one or more of phosphoric acid, hydrofluoric acid, hydrochloric acid, and nitric acid, wherein the concentration range of phosphoric acid is 0~4 mol / L, the concentration range of hydrofluoric acid is 0~2 mol / L, the concentration range of hydrochloric acid is 0.5~2 mol / L, and the concentration range of nitric acid is 0~2 mol / L. The solid-liquid mass ratio for pickling is 1:2~10, and the pickling environment can be atmospheric pickling at 40℃~99℃ or hot-press pickling at 100℃~200℃. The filtration process employs one or more of the following: a thickener, a vacuum filter press, and a plate and frame filter press. The washing process involves repeatedly rinsing the acid-washed quartz with deionized water until the pH of the filtrate is greater than 6.

5. The drying process employs one or more of the following methods: freeze drying, vacuum drying, and electrothermal drying.

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